Transport tanks are provided with armatures, such as filling and discharging valves which are attached to the tank jacket and are sometimes expensive and sensible and which must be protected against external influences and unauthorized manipulation. Risks resulting from damaged or torn-off armatures are considerable, particularly when hazardous goods are transported. It is therefore common to protect such armatures by a surrounding armature box which is mounted on the tank jacket and closed by a flap.
Armature boxes of this type must offer sufficient protection against salt water from the road, sea water, spilled aggressive liquids and other obnoxious environmental influences, on the one hand, and shocks from sharp-edged objects (such as fork lift prongs, crane harnesses) and other mechanical influences, on the other hand. Moreover, they should be as light-weight as possible to avoid an unnecessary increase of the tare weight of the tank.
Conventional armature boxes which are either fixedly welded to the tank jacket or are mounted on reinforcing plates that are in turn welded on the tank jacket, meet the above requirements only insufficiently. In most cases, they are formed as thin-walled sheet metal boxes and therefore provide but unsatisfactory protection against mechanical damage. Where massive steel-tube structures are employed, they increase the tare weight of the tank.
A further disadvantage of common armature boxes resides in the fact that they cause undesired additional thermal stress on the tank when welded to the tank jacket, or involve additional manufacturing costs when mounted on reinforcing plates.
To save weight, and in view of the limited space available, armature boxes should be as small as possible. As a result, they surround the armatures relatively closely which in the prior art results in the further difficulty that they impede the installation of the armatures.